Clamp On or Set Screw Gas Block

[ViniVidivici]

I have used Aero Precision and Ballistic Advantage.

There are cheaper ones out there, but I suspect it doesn't pay to skimp in this area. I like cheap parts, but I'd be worried about stripped threads, things being out of spec, etc. with cheaper blocks.

[1168]

Pinned, clamp on, set screw, doesn’t really matter if its under a handguard, the port is aligned correctly, and threadlocker is used. I like pinned because its super easy and I almost can’t mess it up when I order a barrel that comes with a pinned block. I also hate tiny allen screws. No rocksett or loctite required with pinned. If I have a barrel with no gas block or dimple, I use a dimple jig with a set screw block because they tend to be low profile. With a pinned FSB, I shave it.


The M4 and M16 used taper pinned at least partly because the front sight base/gas block assembly is exposed, and Joe will inevitably drop his rifle, and/or tinker with anything that has a screw. “Look, Sergeant, I figured out how to clean my gas port!” And some idiot would probably be inspecting gas tubes at weapon turn-in.

This is of course just my opinion.

[MistWolf]

I use set screw gas blocks. They take up less room.

I think a clamp on might hold more securely but they are bulkier and sometimes the screws will shear.

[JohnXDm]

Set screws into dimples is the way to go. I've dimpled all of my builds with the SLR jig. It has multiple choices to match the spacing between your gas block set screws. It uses a pointed set screw that you line up with your barrel gas port hole. Then just turn the block over and drill your dimples using the guide. Make sure that you get one for the barrel diameter that you are using. .75 is the most common. Measure the spacing on your gas block set screws, select the correct pattern on the jig. Very easy. .50 set screw spacing is very common but varies between manufacturers.

The dimples guide the set screw into their seat. Ensures proper secure alignment. Simple to use.

https://slrrifleworks.com/index.php?...ry&path=57_129

[Cokeman]

I have used Aero Precision and Ballistic Advantage.

There are cheaper ones out there, but I suspect it doesn't pay to skimp in this area. I like cheap parts, but I'd be worried about stripped threads, things being out of spec, etc. with cheaper blocks.

I’ve been looking at this for ne for $20 but can’t decide.

https://ballisticadvantage.com/750-l...lock-blem.html

[JohnXDm]

They never say what the blemish is. Cosmetic, who cares but problems with the ports can be a pain in the cash.

[ViniVidivici]

I would definitely get that one, the blem isn't going to be anything that affects function. That's a good deal.

[Clint]

There are cheaper ones out there, but I suspect it doesn't pay to skimp in this area. I like cheap parts, but I'd be worried about stripped threads, things being out of spec, etc. with cheaper blocks.

In reality, skimping anywhere in the gas system can cause issues.

The most common issue with cheap gas blocks is over sized bores for both the barrel and gas tube.

Loose bores cause excess gas leakage and variability in gas drive.

[BamaAR]

You won’t be able to use the cuts on the barrel from the removed FSB. I was referring to a virgin gas block and barrel.
You should be able to use set screws however.
Have you considered shaving the FSB if it will fit under your rail?

Have thought about it, actually and may go that route.

[boltcatch]

The key is having a dimple opposite the gas port to properly align the gas block.

With set screw blocks, the rear screw locates on the dimple, while clamp on blocks generally need to be eyeballed.

You do have to eyeball it, but designs with a split on the bottom typically have a hole drilled through the split (created as part of the step to make the gas hole) that can be visually aligned with the barrel dimple.

Springing for a nice gas block of whatever type you get is very much worth it, I've seen too many cheap gas blocks leak like crazy. Sparks going downrange, won't seal up even after 1k rounds.